FERMENTATION. 243 



of the clear, filtered 'must' of the grape be so boiled 

 as to destroy such germs as it may have contracted from 

 the air or otherwise. In contact with germless air the 

 uncontaminated must never ferments. All the mate- 

 rials for spontaneous generation are there, but so long 

 as there is no seed sown, there is no life developed, and 

 no sign of that fermentation which is the concomitant 

 of life. Nor need you resort to a boiled liquid. The 

 grape is sealed by its own skin against contamination 

 from without. By an ingenious device Pasteur has ex- 

 tracted from the interior of tlie grape its pure juice, 

 and proved that in contact with pure air it never 

 acquires the power to ferment itself, nor to produce 

 fermentation in other liquids.' It is not, therefore, in 

 the interior of the grape that the origin of the life 

 observed in the vat is to be sought. 



What then is its true origin ? This is Pasteur's 

 answer, which his well-proved accuracy renders worthy 

 of all confidence. At the time of the vintage micro- 

 scopic particles are observed adherent, both to the outer 

 surface of the grape and to the twigs which support the 

 grape. Brush these particles into a capsule of pure 

 water. It is rendered turbid by the dust. Examined 

 by a microscope, some of these minute particles are 

 seen to present the appearance of organized cells. 

 Instead of receiving them in water, let them be brushed 

 into the pure inert juice of the grape. Forty-eight 

 hours after this is done, our familiar Torula is observed 

 budding and sprouting, the growth of the plant being 

 accompanied by all the other signs of active fermenta- 

 tion. What is the inference to be drawn from thit 



' The liquids of the healthy animal body are also sealed fror 

 external contamination. Pure blood, for example, drawn with due 

 precautions from the veins, will never ferment or putrefy in contact 

 with pure air. 



